51% of blockchain

1. blockchain mainly solves the trust and security problems of transactions, so it proposes four technological innovations to solve this problem:
(1) distributed ledger, that is, transaction bookkeeping is completed by multiple nodes distributed in different places, and each node records complete accounts, so they can participate in monitoring the legitimacy of transactions, At the same time, they can testify together
different from traditional distributed storage, the uniqueness of distributed storage of blockchain is mainly reflected in two aspects: one is that each node of blockchain stores complete data according to block chain structure, while traditional distributed storage generally stores data in multiple copies according to certain rules. Second, the storage of each node in the blockchain is independent and has the same status, which relies on the consensus mechanism to ensure the consistency of storage, while the traditional distributed storage generally synchronizes data from the central node to other backup nodes[ 8]
no single node can record the account data separately, so as to avoid the possibility that a single bookkeeper is controlled or bribed to record false accounts. In theory, unless all the nodes are destroyed, the accounts will not be lost, so as to ensure the security of the account data
(2) asymmetric encryption and authorization technology, the transaction information stored on the blockchain is public, but the account identity information is highly encrypted, which can only be accessed under the authorization of the data owner, thus ensuring the data security and personal privacy
(3) consensus mechanism is how to reach a consensus among all accounting nodes to determine the validity of a record, which is not only a means of identification, but also a means of preventing tampering. Blockchain proposes four different consensus mechanisms, which are suitable for different application scenarios and achieve a balance between efficiency and security
the consensus mechanism of blockchain has the characteristics of "the minority is subordinate to the majority" and "everyone is equal", in which "the minority is subordinate to the majority" does not completely refer to the number of nodes, but also can be the computing power, the number of shares or other characteristics that can be compared by computers“ "Everyone is equal" means that when the nodes meet the conditions, all nodes have the right to put forward the consensus results first, and then directly recognized by other nodes, and finally may become the final consensus results. Taking bitcoin as an example, the workload proof is adopted. Only when more than 51% of the accounting nodes in the whole network are controlled can a nonexistent record be forged. When there are enough nodes in the blockchain, this is basically impossible, thus eliminating the possibility of fraud.
(4) smart contract, which is based on these trusted and tamperable data, can automatically execute some pre-defined rules and terms. Take insurance as an example. If everyone's information (including medical information and risk occurrence information) is true and reliable, it is easy to carry out automatic claim settlement in some standardized insurance procts

2. 1、 Decentralization:
blockchain technology does not rely on additional third-party management institutions or hardware facilities, and there is no central control. In addition to the self-contained blockchain itself, each node realizes information self verification, transmission and management through distributed accounting and storage. Decentralization is the most prominent and essential feature of blockchain< Second, openness:
the foundation of blockchain technology is open source. In addition to the private information of all parties to the transaction is encrypted, the data of blockchain is open to all. Anyone can query blockchain data and develop related applications through the open interface, so the information of the whole system is highly transparent< Third, independence:
based on consensus specifications and Protocols (similar to various mathematical algorithms such as hash algorithm used by bitcoin), the whole blockchain system does not rely on other third parties, and all nodes can automatically and safely verify and exchange data in the system without any human intervention< Fourth, security:
as long as 51% of all data nodes cannot be controlled, the network data cannot be arbitrarily controlled and modified, which makes the blockchain itself relatively safe and avoids subjective and artificial data changes
5. Anonymity:
unless there are legal requirements, technically speaking, the identity information of each block node does not need to be disclosed or verified, and information transmission can be carried out anonymously
Digital China is the first major development strategy explicitly put forward in the report of the 19th National Congress of the Communist Party of China. The application of digital technology represented by cloud computing, big data and mobile Internet is no longer limited to the economic field, but widely penetrated into all aspects of public services, social development and people's life, which requires macro coordination, overall control and integrated development
with the deepening of a new round of scientific and technological revolution and instrial change, the tide of digital economy in the world is unstoppable. The development of digital economy has become a global consensus, known as the key to the fourth instrial revolution
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3. Decentralized
e to the use of Distributed Accounting and storage, there is no centralized hardware or management organization, the rights and obligations of any node are equal, and the data blocks in the system are jointly maintained by the nodes with maintenance function in the whole system
openness
the system is open, in addition to the private information of all parties to the transaction is encrypted, the data of the blockchain is open to all, and anyone can query the blockchain data and develop related applications through the open interface, so the information of the whole system is highly transparent
autonomy
blockchain adopts consensus based specifications and Protocols (such as a set of open and transparent algorithms) to enable all nodes in the whole system to exchange data freely and safely in a de trusted environment, so that the trust in "people" is changed into the trust in machines, and any human intervention does not work
information cannot be tampered with
once the information is verified and added to the blockchain, it will be stored permanently. Unless more than 51% of the nodes in the system can be controlled at the same time, the modification of the database on a single node is invalid, so the data stability and reliability of the blockchain are extremely high<
anonymity
since the exchange between nodes follows a fixed algorithm, their data interaction does not need to be trusted (the program rules in the blockchain will judge whether the activity is effective by themselves), so the counterparties do not need to trust themselves by disclosing their identities, which is very helpful for credit accumulation

4. Bitcoin market suddenly soared, and now you can buy it. But you have to buy by yourself. Think about it, because bitcoin is a virtual currency. Market uncertainty, buy carefully.

5. In a simple explanation, 51% attack is also called majority attack. It means that malicious miners control more than 50% of the hash rate of the blockchain network, and then attack the network and take over the blockchain network, so that criminals can reverse transactions, stop payment or prevent new transactions from being confirmed
for more information about 51% attacks, you can learn about them on the password finance network,